System and method for processing a common cable signal using a low-pass filter tap

ABSTRACT

A method for processing an input signal is disclosed. The method includes receiving an input signal. The method also includes applying a first transfer function to the input signal to produce a first signal, wherein the first transfer function exhibits a high pass characteristic. The method further includes applying a second transfer function to the input signal to produce a second signal, the second transfer function exhibiting a low pass characteristic.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 10/373,536 entitled “SYSTEM AND METHOD FOR PROCESSING A COMMONCABLE SIGNAL USING A LOW-PASS FILTER TAP,” filed Feb. 23, 2003, andissued Oct. 30, 2012 as U.S. Pat. No. 8,302,147 the disclosure of whichis hereby incorporated by reference herein in its entirety.

TECHNICAL FIELD OF THE INVENTION

This invention relates in general to cable receivers, and moreparticularly to a system and method for processing a common cable signalusing a low-pass filter tap.

BACKGROUND OF THE DISCLOSURE

Open Cable standards define four channels: the Forward ApplicationTransport (FAT) channel, National Television Standards Committee (NTSC)analog channel, Forward Data Channel (FDC), and the Reverse Data Channel(RDC). The FAT and NTSC analog signals are considered in-band signals,while the FDC and RDC are considered out-of-band. In Open Cable systems,a common cable carries both the FAT and FDC signals to a receiver, suchas a set-top box, that extracts signals for communication to respectivetuners. To separate the signals, the set-top box typically uses adirectional coupler, which imparts a signal loss of approximately 1decibel (dB) to the FAT signal and approximately 10 dB to the FDCsignal.

SUMMARY OF THE DISCLOSURE

In accordance with the present invention, the disadvantages and problemsassociated with amplifying and dividing common cable channels have beensubstantially reduced or eliminated. In particular, certain embodimentsof the present invention provide a system and method for processing acommon cable signal using a low-pass filter tap.

In accordance with one embodiment of the present invention, a method forprocessing an input signal includes receiving an input signal. Themethod also includes applying a first transfer function to the inputsignal to produce a first signal, wherein the first transfer functionexhibits a high pass characteristic. The method further includesapplying a second transfer function to the input signal to produce asecond signal, the second transfer function exhibiting a low passcharacteristic.

In accordance with another embodiment of the present invention, alow-pass filter tap includes a resistor and an inductor. The resistorhas a first resistor terminal and a second resistor terminal, and thefirst resistor terminal receives an input signal. The inductor has afirst inductor terminal coupled to the second resistor terminal and asecond inductor terminal. The low-pass filter tap produces an outputsignal comprising at least a portion of the input signal.

In another embodiment of the present invention, an integrated circuitincludes an in-band tuner and an amplifier. The in-band tuner receives afirst signal that includes a plurality of content channels and extractsinformation from a selected content channel. The amplifier receives asecond signal that includes a plurality of data channels, amplifies thesecond signal, and communicates the second signal to an out-of-bandtuner.

Particular embodiments of the present invention may include importanttechnical advantages, some of which are enumerated below. Othertechnical advantages of the present invention will be readily apparentto one skilled in the art from the following figures, descriptions, andclaims. Moreover, while specific advantages are enumerated here,particular embodiments may include all, some, or none of the enumeratedadvantages.

Important technical advantages of certain embodiments of the presentinvention include reducing loss to the Forward Application Transport(FAT) signal. Because the FAT signal communicates content that requireshigh-quality transmission, it is particularly desirable to maintain asmuch power as possible in the FAT signal. Certain embodiments of thepresent invention extract the FDC channel with significantly less lossto the overall power of the FAT signal, and in particular, significantlyless loss at higher frequencies.

Other important technical advantages of certain embodiments of thepresent invention include adaptability to existing standards. Certainembodiments of the present invention exhibit performance characteristicsin compliance with existing standards. For example, the amplifieramplifying the FDC channel may present a 75-ohm output impedance, whichis compatible with out-of-band tuners commonly used in set-top boxes.Furthermore, the narrower frequency band FDC output of certainembodiments of the present invention makes it easier for amplifiers tobe designed in compliance with linearity requirements.

Yet another technical advantage of certain embodiments of the presentinvention is providing an integrated circuit that includes both anin-band tuner and an amplifier for the FDC signal. Certain embodimentsinclude a tuner-amplifier combination on a single integrated circuit,providing a convenient solution for manufacturing set-top boxes. Suchembodiments may provide cost savings by replacing existing componentsthat perform FDC amplification after the FDC signal is extracted.

Other technical advantages of the present invention will be readilyapparent to one skilled in the art from the following figures,descriptions, and claims. Moreover, while specific advantages have beenenumerated above, various embodiments may include all, some, or none ofthe enumerated advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and itsadvantages, reference is now made to the following description, taken inconjunction with the accompanying drawings, in which:

FIG. 1 illustrates a receiver in accordance with a particular embodimentof the present invention;

FIG. 2 illustrates a receiver in accordance with another embodiment ofthe present invention;

FIG. 3 is a frequency spectrum illustrating Forward ApplicationTransport (FAT) and Forward Data Channel (FDC) frequency bands andchannels;

FIG. 4 is a diagram of transfer functions applied to an input signal bythe receiver of FIG. 1, plotted as a function of frequency; and

FIG. 5 is a flow chart illustrating one example of a method of channelprocessing in the receiver of FIG. 1.

DETAILED DESCRIPTION OF THE DISCLOSURE

FIG. 1 shows a particular embodiment of a receiver 100 used, forexample, in a set-top box (STB), television, personal computer, or otherdevice to receive common cable signals 122. In the depicted embodiment,receiver 100 includes a diplexer 112 that receives signals from areverse data channel 113, a low-pass filter tap 102, an integratedcircuit 104 that includes both in-band tuner 106 and a buffer amplifier108, and an out-of-band tuner 110. In general, low-pass filter tap 102processes the common cable signal 122 to produce two output signals: afirst output signal 124 for in-band tuner 106 and a second output signal126 for out-of-band tuner 110. Buffer amplifier 108 amplifies the secondsignal 126. Tuners 106 and 110 receive signals 124 and 126,respectively, and extract appropriate information therefrom. Receiver100 embodies improved techniques for separating signals 124 and 126 fromcommon cable signal 122 and amplifying signal 126 for out-of-band tuner110.

Various cable standards specify methods for carrying both in-bandcontent and out-of-band data within a common cable signal. Although theterms in-band and out-of-band may generally refer to particularfrequency bands, the term “in-band” may also refer generically to anychannel assigned to carry content signals such as digital programming.Similarly, “out-of-band” may refer generically to channels that carryinformation that is considered data, as differentiated from content.“Common cable signal” refers to any signal that carries both in-band andout-of-band information in the same signal.

One example of a cable standard is the Open Cable standard “Open CableSet-top Terminal CORE Functional Requirements for Bi-Directional Cable,”identified by reference number CFR-OCS-BDC-INT02-000418. In the OpenCable standard, in-band content is communicated to a set top box (STB)in a Forward Application Transport (FAT) signal, while out-of-band datais communicated in a Forward Data Channel (FDC). Additionally, in-bandsignals may be communicated in National Television Standards Committee(NTSC) analog signals, so wherever the subsequent description may makereferences to FAT signals or FAT tuners, it should be understood thatthe description applies equally well to NTSC analog signals and NTSCtuners in place of, or in addition to, the associated FAT signals andtuners. The FAT signal carries cable content that includes digitizedvideo and audio data for a large number of channels. Because customersare accustomed to a high quality level for cable content, it isdesirable to preserve as much power as possible in the FAT signal toprovide the highest quality of content reproduction possible at the STB.The FDC carries out-of-band data, such as program guides, menus,authorization for pay-per-view selections, and other information to theSTB. It is typically less important to maintain a high level of power onthe FDC. In the interest of a more comprehensive disclosure, it may beuseful to note that information may also be communicated from the STB tothe cable provider using a reverse data channel (RDC), such aspay-per-view orders, data communicated by a cable modem, menuselections, information request, or any other suitable data.

According to the Open Cable standard, the FAT signal is assigned to aparticular frequency band, while the FDC is assigned to a narrowersubrange of frequencies on the lower end of the frequency band assignedto the FAT signal. Existing systems use a directional coupler toseparate the FAT signal from the FDC. A directional coupler is asplitter that dives the signal into two signals with unequal power. Thepower loss resulting from splitting the signal is substantially equalacross all frequencies. A typical directional coupler imparts a loss ofapproximately 1 decibel (dB) loss to all frequencies on the signal thatis eventually provided to a FAT tuner, and a loss of approximately 10 dBto the signal that is eventually provided to an FDC tuner. Onedisadvantage to such methods is that the power used to communicate thehigh-frequency components of the common cable signal to the FDC tuner iswasted, since the FDC tuner does not tune to frequencies outside of theFDC band. Furthermore, this wasted power also represents a loss to theavailable power of the higher-frequency channels in the FAT signalprovided to the FAT tuner, which may contribute to lower-qualityreproduction of the content stored in the FAT signal. The Open Cablestandard, using FAT for content and FDC for data, is one of manypossible techniques for communicating data and content in a common cablesignal, and the selection of this particular example should not be takento exclude other suitable standards from the following description.

Receiver 100 provides significant advantages over existing receiversused in STBs, televisions, personal computers and other devicesreceiving cable signals. Receiver 100 uses a low-pass filter tap 102 toextract from common cable signal 122 a first signal 124 that iscommunicated to in-band tuner 106 and a second signal 126 that iscommunicated to out-of-band tuner 110. Receiver 100 uses signal powermore efficiently by allocating more power to the higher frequency rangesprimarily used by in-band tuner 106 on the in-band path and more powerto the lower frequencies used by out-of-band tuner 110 on theout-of-band path. In addition, the use of low-pass filter tap 102 toextract signal 122 presents significant cost advantages over directionalcouplers.

Diplexer 112 comprises one or more components used to receive commoncable signals from a cable provider. Diplexer 112 may include anysuitable collection of active and/or passive components for receivingcommon cable signal 122 and communicating the signal to tap 102.Diplexer 112 also receives signals from reverse data channel 113 forcommunication back to the cable provider. One important consideration inthe design of receiver 100 is limiting the ratio of power reflected fromtap 102 back to diplexer 112 as compared to the input power of commoncable signal 122, a quantity known as “return loss.” Various cablestandards specify a maximum allowable return loss in terms of theoriginal signal power. For example, a particular standard might mandatea return loss better than 10 dB.

Low-pass filter tap 102 includes a resistor 114, inductors 116A and116B, and a shunt capacitor 118. In combination with the othercomponents of low-pass filter tap 102, resistor 114 selectively extractsat least a portion of signal 122 so the lower frequencies areselectively communicated on the out-of-band path, while the higherfrequency components are relatively attenuated. The resistance value ofresistor 114 may be selected to keep the noise introduced intoout-of-band signal 126 below a predetermined level.

Inductors 116A and 116B have inductance values according to the desiredfrequency band, but other design considerations may be taken intoaccount in the selection of inductance values. For example, the valuesof inductors 116A and/or 116B may be selected to control the amount ofreturn loss. Although the depicted embodiment includes two inductors116A and 116B, low-pass filter tap 102 may include more or fewerinductors as needed or desired.

Shunt capacitor 118 appears as a short to ground 120 for high frequencysignals. The effect of capacitor 118 is to attenuate the signal levelabove a certain frequency, thus narrowing the frequency band of outputsignal 126 from tap 102. Other considerations, such as return loss, mayalso be considered in determining the value of capacitor 118.

The narrower frequency band of signal 126 communicated to amplifier 108has some technical advantages. First, it prevents power used to amplifyout-of-band signal 126 from being wasted on extraneous frequencies notdetected by out-of-band tuner 110. Second, it reduces the range offrequencies to which amplifier 108 must respond. This is advantageousbecause certain standards require amplifier 108 to respond with acertain degree of linearity over the entire range of amplifiedfrequencies and such linearity is easier to provide over a narrowerfrequency band.

The depicted embodiment of low-pass filter tap 102 is only one of manypossible embodiments, using any combination of resistors, inductors,capacitors, or other suitable electronic components. One importantcharacteristic of low-pass filter tap 102 is the frequency-selectivetapping function performed by resistor 114, inductors 116A and 116B, andcapacitor 118. While low-pass filters may be used in conjunction withthe directional coupler of existing system to narrow the frequency bandpresented to amplifier 108 for the reasons discussed above, the powerremoved from the signal at higher frequencies is wasted. By contrast,tap 102 selectively extracts frequencies, thus conserving signal powerin the higher frequencies of the in-band range.

Integrated circuit 104 comprises a silicon chip that includes in-bandtuner 106 and buffer amplifier 108. Existing systems provide in-bandtuners on integrated circuits that receive signals from directionalcouplers, but such systems require separate off-chip hardware to amplifythe output of the directional coupler so that the out-of-band signal maybe provided to an out-of-band tuner. One advantage of receiver 100 isthat receiver 100 provides an integrated solution that efficientlyprocesses input signal 122 into in-band signal 124 and out-of-bandsignal 126. This allows receiver 100 to function with conventionalout-of-band tuners 110 without requiring any off-chip hardware toamplify the output signal for out-of-band tuner 110.

In-band tuner 106 comprises any suitable component or components forextracting information from a particular channel within the in-bandsignal. Particular embodiments of in-band tuners 106 use components suchas upconverters, downconverters, attenuators, amplifiers, demodulators,or other suitable electronic components.

Buffer amplifier 108 comprises any suitable hardware and/or software foramplifying out-of band signal 126 for presentation to out-of-band tuner110. In the depicted embodiment, buffer amplifier 108 is fabricated on asilicon chip 104 with in-band tuner 106. In terms of performance, bufferamplifier 108 may meet certain requirements in order to comply withvarious standards. Various considerations in the design of amplifier 108include noise figure, reverse isolation, linearity, gain, and othersuitable considerations.

Another consideration is reverse isolation of amplifier 108. Oscillatorsused in out-of band tuner 110 may produce a signal that bleeds backthrough amplifier 108. Reverse isolation refers to attenuating thebleed-back signal to prevent interference with other signals in receiver100. Directional couplers provide some reverse isolation naturally, butlow-pass filter tap 102 generally provides less reverse isolation than atypical directional coupler. As a result, tap 102 and amplifier 108 mayinclude values that are selected to reverse-isolate out-of-band tuner110.

Out-of-band tuner 110 comprises any suitable component for extractinginformation from channels within the frequency range of the out-of-bandsignal. Out-of-band tuner 110 may include any suitable electroniccomponents, including those used in in-band tuner 106, and may beselected from any of a wide variety of standard parts used in receiversin conjunction with directional couplers and amplifying hardware. Oneadvantage of certain embodiments of receiver 100 is providingout-of-band tuner 110 with a clear signal 126 due to efficient power usefrom the use of low-pass filter tap 102. This reduces the chance thatthe out-of-band tuner 110 will distort the output from out-of-bandsignal 126, lose information, or otherwise fail to properly extractinformation from the out-of-band signal.

In operation, diplexer 112 exchanges information with a cable providerby receiving common cable signals 122 (including in-band and out-of-bandinformation) and communicating RDC signals 113 back to the cableprovider. Diplexer 112 communicates common cable signal 122 to low-passfilter tap 102. Low-pass filter tap 102 selectively draws low frequencycomponents of common cable signal 122 into signal 126 communicated tobuffer amplifier 108.

Signal 124, which represents the remaining portion of common cablesignal 122 after signal 126 is drawn off, continues to in-band tuner106. Signal 124 is somewhat attenuated in the lower frequency rangebecause of the power drain caused by extracting signal 126 from commoncable signal 122. However, at high frequencies, relatively little lossis imparted to signal 124 as a result of the extraction of signal 126.Thus the power in common cable signal 122 is efficiently preserved for asignificant portion of the in-band frequencies. This enables in-bandtuner 106 to more effectively extract content from in-band channels.

Performance metrics for receiver 100 may vary depending on theparticular type, values, and arrangement of the components of receiver100, and design choices may be affected by industry standards, costconsiderations, intended use and a variety of other considerations. Forthe sake of providing a benchmark, the following example is presented,but it should be understood that this embodiment is only one of manypossible examples. In a particular embodiment, resistor 114 has R=100ohms, inductor 116A has L=560 nH, inductor 116B has L=270 nH, andcapacitor 118 has C=3 pF.

FIG. 2 shows another embodiment of receiver 200 that uses a directionalcoupler 202 in place of low-pass filter tap 102. Diplexer 204, reversedata channel 205, out-of-band tuner 206, and in-band tuner 208 representthe same components as the like components shown in FIG. 1. Thedifferences are in low-pass filter 210 and amplifier 212 in integratedcircuit 214. Because directional coupler 202 is used, low-pass filter210 does not require a resistor. Instead, low-pass filter 210 usesinductors, capacitors, and any other suitable components to attenuatethe component of the signal outside of the desired frequency band forout-of-band tuner 206. Unlike low-pass filter tap 102 of FIG. 1, coupler202 does not preserve the power at higher frequencies in the in-bandsignal 124.

Directional coupler 202 divides a common cable signal 218 into a firstsignal 220 for in-band tuner 208 and a second signal 222 for out-of-bandtuner 206.

Because the quality of in-band signals is more likely to be degraded byinsufficient power than out-of-band signals, directional coupler 202provides most of the power to first signal 220 (typically 1 dB less thancommon cable signal 218) and less power to second signal 222 (typically10 dB less than common cable signal 218). The loss imparted by coupler202 is essentially uniform across all frequencies in both paths.

Amplifier 212 may have different characteristics than amplifier 108.However, amplifier 212 may also be suitably designed to be compatiblewith low-pass filter tap 102. This provides advantageous versatility forthe component, since integrated circuit 214 may then be incorporatedinto receivers that use either directional couplers 202 or low-passfilter taps 102. Even without adapting amplifier 212 for use with bothdirectional couplers 202 and low-pass filter taps 102, integratedcircuit 214 that includes in-band tuner 208 and amplifier 212 stillprovides advantages by reducing the number of components required toprovide an amplified signal to out-of-band tuner 206 and by reducing theoverall amount of space and cost required for a set-top box receiver.

FIG. 3 shows a frequency spectrum 300 according to the Open Cablespecification. The FAT band 302 encompasses a nominal frequency rangefrom 54 MHz to 864 MHz. Within the FAT band 302, the FDC band 304 ispermitted within the range of 70 to 130 MHz. As might be expected,channels 306 for FAT communication require a larger bandwidth in orderto guarantee the continuous delivery of large amounts of visual andaudio information. Consequently, FAT channels 306 have a bandwidth of 6MHz. In-band tuner 106 or 208 requires a relatively high power level inorder to capture all of the content in a channel accurately. In general,the higher the power level, the more effective in-band tuner 106 will beat performing its task.

By contrast, the FDC channels 308 carry less information and requireless bandwidth. FDC channels 308 are easier to detect, and can bedistinguished more readily at a lower power level. However, because FDCinformation may be extremely sensitive to the loss of any relevant data,it is important that the power is sufficient to allow a high degree ofaccuracy in extracting information from FDC channels. In a particularembodiment, receiver 100 serves both purposes by drawing off sufficientpower for the FDC signal at low frequencies while limiting the reductionin power level for high frequency signals in the FAT signal.

FIG. 4 is a diagram that illustrates the transfer functions 324 and 326of low-pass filter tap 102 with respect to signals 124 and 126,respectively, and input signal 122 plotted as a function of frequency.The transfer function represents the ratio of the power of therespective output signal to the power of the input signal plotted as afunction of frequency. Thus, the value of the transfer function at anypoint represents the ratio of the output power to the input power at aparticular frequency. The curves are approximations intended toillustrate the general relationship of each signal's transfer functionversus frequency, rather than to illustrate a precise numerical ormathematical relationship.

For ease in describing the behavior of signals 124 and 126 at high andlow frequencies, a cutoff frequency 328 may be defined to separate twofrequency ranges: a high-frequency range 330 above cutoff frequency 328and a low-frequency range 332 below cutoff frequency 328. Cutofffrequency 328 may represent any selected frequency relevant to assessingthe power characteristics of signals 124 and 126, and may include acharacteristic cutoff frequency for low-pass filter tap 102, a defineddegree of attenuation for signal 126, or any other suitable frequency.

The characteristics of the transfer function 324 for tap 102 withrespect to first signal 124 and input signal 122 may be described invarious ways. Generally, transfer function 324 exhibits a high passcharacteristic, so that a greater degree of attenuation is imparted tolow-frequency channels than high-frequency channels. For purposes ofquantifying the degree of attenuation, the minimum value 334 of transferfunction 324 may be useful for comparing the signal 124 to a comparableoutput signal 220 produced by directional coupler 202. In particularembodiments of receiver 100, minimum value 334 may be comparable to theuniform value of the transfer function of directional coupler 202 withrespect to output signal 220.

It may also be useful to consider the average values of transferfunction 324 in frequency ranges 330 and 332. Average values of transferfunction 324 may be calculated using any suitable technique, such asintegrating over the frequency range and dividing by the width of thefrequency range. In high-frequency range 330, the average value 336 oftransfer function 324 is close to zero dB (no attenuation), and mayadvantageously be significantly higher than the corresponding uniformvalue of the transfer function of directional coupler 202 with respectto signal 220. In low-frequency range 332, the average value 338 oftransfer function 324 is lower than the average value 336 inhigh-frequency range 330 and the average value 337 across allfrequencies of signal 124, but may advantageously be higher than theuniform value of the transfer function of directional coupler 202 withrespect to signal 220. Thus, receiver 100 may provide a significantlyhigher transfer function for channels in high-frequency range 330 ascompared to directional coupler 202, as well as a comparable or highertransfer function for channels in low-frequency range 332.

Characteristics of the transfer function 326 for tap 102 with respect tosecond signal 126 and input signal 122 may be similarly described.Generally, transfer function 326 exhibits a low pass characteristic, sothat a greater degree of attenuation is applied to high frequencies thanlow frequencies. Of particular interest is the fact that tap 102 impartsa significantly greater degree of attenuation to frequencies outside ofa desired frequency band from which out-of-band tuner 110 extractschannels. Diagram 320 illustrates the frequency range assigned toout-of-band signals, indicated by boundary lines 340A and 340B. Theminimum value 342 of the transfer function in the out-of-band frequencyrange provides a useful indication for determining whether out-of-bandtuner 110 will have sufficient power to extract information from allchannels in the out-of-band range. Minimum value 342 may also be used tocompare the transfer function to that of the corresponding output signal222 from directional coupler 202.

Average values 344 and 346 may also be determined for transfer function326 in low-frequency range 332 and high-frequency range 330,respectively, and an average value 345 for the transfer function overall frequencies of signal 126 may also be determined. Comparing averagevalue 344 at low frequencies to average value 346 at high frequenciesand/or overall average value 345 provides a useful indication of therelative effectiveness of tap 102 at isolating the relevant frequenciesthat are useful to out-of-band tuner 110. Average value 344 may also becompared to the value of the transfer function for a correspondingoutput signal 222 of directional coupler 202, thus providing someindication of the relative effectiveness of tap 102 as compared todirectional coupler 202.

The depicted diagram 320 is only one example of numerous possible waysof characterizing the output signals 124 and 126 generated by tap 102.Particular performance advantages of tap 102 relative to directionalcoupler 102 need not be present in all embodiments, and are includedonly for the purpose of illustration. Various embodiments may producesignals 124 and 126 with different transfer functions, differentrelationships between transfer function and frequency, and differentabsolute, average, and relative transfer functions. In particular, thecharacteristic values of the transfer function of signals 124 and 126 inhigh-frequency range 330 and low-frequency range 332 may vary greatlydepending on the particular embodiment selected. Consequently, therelationships depicted in diagram 320 should be viewed as particularexamples of some of the numerous possible examples of the transferfunction relationship between signals 122, 124, and 126. Furthermore,although the use of tap 102 has been described as one technique forproducing transfer functions with desired characteristics, such ashaving a higher average value 344 in low-frequency range 332 for signal126, the use of this particular example need not exclude the use ofother techniques for applying transfer functions with similarcharacteristics.

FIG. 5 is a flowchart illustrating the processing a particular channelassociated with in-band signal 124 or out-of-band signal 126. Receiver100 receives common cable signal 122 that includes the particularchannel using diplexer 112 at step 402. What happens to the particularchannel next is determined by the frequency of the channel in relationto a cutoff frequency, as shown in decision step 404. The cutofffrequency is defined as the frequency beyond which the attenuation inin-band signal 124 is not considered significant, which may be aparticular level of attenuation, a percentage variation below a certainthreshold, or any other suitable metric beyond which in-band signal 124is not considered to be attenuated.

If the channel frequency is above the cutoff frequency, meaning that thechannel is an in-band channel, the channel is communicated in signal 124to in-band tuner 106 without substantial attenuation at step 409.In-band tuner 106 then extracts information the channel at step 410. Themethod then repeats for that channel from step 402 for as long asinformation continues to be transmitted on the channel, as shown bydecision step 411.

If the channel frequency is below the cutoff frequency, then whathappens to the channel will depend on whether the channel is an in-bandchannel or an out-of-band channel, as shown by decision step 406. If thechannel is an in-band channel, the channel is attenuated at step 412 dueto a portion of common cable signal 122 being drawn off by low-passfilter tap 102. The attenuated channel is then communicated to in-bandtuner 106 as part of signal 124 at step 409, and in-band tuner 106extracts information from the channel at step 410. The method thenrepeats from step 402 as long as information continues to be transmittedon the channel.

If the channel is an out-of-band channel, then the channel inserted intolow-pass filter tap 102 as part of signal 126 at step 408. Capacitor 118attenuates extraneous high-frequency components of signal 126 at step414. Amplifier 108 then amplifies signal 126, including the out-of-bandchannel, at step 416, and communicates signal 126 to out-of-band tuner110 at step 418. Out-of-band tuner 110 extracts information from thechannel at step 420, and the method repeats from step 402 as long asinformation continues to be transmitted on the channel.

The described method of operation is only one example of numerouspossible embodiments. Particular steps may be omitted, added, orperformed in a different order, and the method may be performed usingdifferent components or in a different device than the one described. Inparticular, the described method does not exclude any other method ofoperation or technique consistent with those described above inconjunction with any other embodiments.

Although the present invention has been described with severalembodiments, variations, alterations, a myriad of transformations,changes, and modifications may be suggested to one skilled in the art,and it is intended that the present invention encompass such changes,variations, alterations, transformations, and modifications as fallwithin the scope of the appended claims.

What is claimed is:
 1. A method for reducing power consumed by tuneroperation, said method comprising: extracting, from an input signal, afirst signal comprising a plurality of content channels and a secondsignal comprising a plurality of data channels; transmitting said firstsignal to an in-band tuner operable to receive said first signalcomprising a plurality of content channels and further operable toextract information from a selected content channel; transmitting saidsecond signal to an out-of-band tuner operable to receive said secondsignal comprising said plurality of data channels and further operableto extract information from a selected data channel; and receiving saidextracted second signal comprising said plurality of data channels at anamplifier, said amplifier operable to amplify said second signal andcommunicate said second signal to said out-of-band tuner.
 2. The methodof claim 1 further comprising: selectively extracting frequencies fromsaid input signal so that more power is allocated to higher frequencieswithin a frequency band used by said in-band tuner and more power isallocated to lower frequencies within a frequency band used by saidout-of-band tuner.
 3. The method of claim 1 further wherein saidextracting is performed by a low pass filter tap.
 4. The method of claim1 further comprising: applying a first transfer function exhibiting ahigh pass characteristic on said input signal to produce said firstsignal; and applying a second transfer function exhibiting a low passcharacteristic on said input signal to produce said second signal. 5.The method of claim 1 further comprising: applying a first transferfunction to produce said first signal, wherein said first transferfunction is characterized by a lower average power value in said firstfrequency band than said average value over all other frequencies insaid first signal; and applying a second transfer function to producesaid second signal, wherein said second transfer function ischaracterized by a higher average power value in said first frequencyband than said average value over all other frequencies in said secondsignal.
 6. The method of claim 1 wherein: said first and second signalsare generated from a common signal by a directional coupler; said firstsignal has a power that is cutoff at a predetermined range above andbelow 1 dB less than an original power of said input signal; and saidsecond signal has a power that is cutoff at a predetermined range aboveand below 10 dB less than said original power of said input signal. 7.An apparatus for reducing power consumed by tuner operation, saidapparatus comprising: at least one processor; and a memory coupled tosaid at least one processor, wherein said least one processor isconfigured to: extract, from an input signal, a first signal comprisinga plurality of content channels and a second signal comprising aplurality of data channels; transmit said first signal to an in-bandtuner operable to receive said first signal comprising a plurality ofcontent channels and further operable to extract information from aselected content channel; transmit said second signal to an out-of-bandtuner operable to receive said second signal comprising said pluralityof data channels and further operable to extract information from aselected data channel; and receive said extracted second signalcomprising said plurality of data channels at an amplifier, saidamplifier operable to amplify said second signal and communicate saidsecond signal to said out-of-band tuner.
 8. The apparatus of claim 7wherein said least one processor is configured to: selectively extractfrequencies from said input signal so that more power is allocated tohigher frequencies within a frequency band used by said in-band tunerand more power is allocated to lower frequencies within a frequency bandused by said out-of-band tuner.
 9. The apparatus of claim 7 wherein saidleast one processor is configured to: instruct a low pass filter tap toperform said extraction.
 10. The apparatus of claim 7 wherein said leastone processor is configured to: apply a first transfer functionexhibiting a high pass characteristic on said input signal to producesaid first signal; and apply a second transfer function exhibiting a lowpass characteristic on said input signal to produce said second signal.11. The apparatus of claim 7 wherein said least one processor isconfigured to: apply a first transfer function to produce said firstsignal, wherein said first transfer function is characterized by a loweraverage power value in said first frequency band than said average valueover all other frequencies in said first signal; and apply a secondtransfer function to produce said second signal, wherein said secondtransfer function is characterized by a higher average power value insaid first frequency band than said average value over all otherfrequencies in said second signal.
 12. The apparatus of claim 7 whereinsaid least one processor is configured to: generate said first andsecond signals from said by input signal using a directional coupler,where; said first signal has a power that uniformly approximately 1 dBless than an original power of said input signal; and said second signalhas a power that uniformly approximately 10 dB less than said originalpower of said input signal.
 13. An integrated circuit, said integratedcircuit comprising: a filter element operable to extract, from an inputsignal, a first signal comprising a plurality of content channels and asecond signal comprising a plurality of data channels; an in-band tuneroperable to receive said first signal comprising a plurality of contentchannels and further operable to extract information from a selectedcontent channel; an out-of-band tuner operable to receive said secondsignal comprising said plurality of data channels and further operableto extract information from a selected data channel; and an amplifieroperable to receive said second channel comprising said plurality ofdata channels from said filter element, and further operable to amplifysaid second signal and communicate said second signal to saidout-of-band tuner.
 14. The integrated circuit of claim 13 wherein; saidfilter element is further operable to selectively extract frequenciesfrom said input signal so that more power is allocated to higherfrequencies within said frequencies used by said in-band tuner and morepower is allocated to lower frequencies within said frequencies used bysaid out-of-band tuner.
 15. The integrated circuit of claim 13 whereinsaid filter element is a low pass filter tap.
 16. The integrated circuitof claim 13 wherein: said first signal is produced by application of afirst transfer function exhibiting a high pass characteristic; and saidsecond signal is produced by application of a second transfer functionexhibiting a low pass characteristic.
 17. The integrated circuit ofclaim 13 wherein: said first signal is produced by application of afirst transfer function, wherein said first transfer function ischaracterized by a lower average power value in said first frequencyband than said average value over all other frequencies in said firstsignal; and said second signal is produced by application of a secondtransfer function, wherein said second transfer function ischaracterized by a higher average power value in said first frequencyband than said average value over all other frequencies in said secondsignal.
 18. The integrated circuit of claim 13 wherein: said first andsecond signals are generated from a common signal by a directionalcoupler; said first signal has a power that uniformly approximately 1 dBless than an original power of said input signal; and said second signalhas a power that uniformly approximately 10 dB less than said originalpower of said input signal.